1. Field of the Invention
The present invention relates to an evaporated fuel treatment apparatus.
2. Background Art
Conventionally, there has been used an evaporated fuel treatment apparatus (hereinafter also referred to as a canister) which temporarily adsorbs a fuel component of evaporated fuel in order to prevent the evaporated fuel from being emitted into the atmosphere from an automobile fuel tank or the like.
In recent years, there has been a demand for the canister to reduce emission of evaporated fuel into the atmosphere. To reduce the emission of evaporated fuel into the atmosphere as described above, as activated carbon filled in the canister, activated carbon has been known, in which the percentage of pores having a diameter of 20 Å or less, in which butane tends to remain, is 20% or less of pores having a diameter of 100 Å or less, and the percentage of pores having a diameter of more than 20 Å to 25 Å or less, which is effective to adsorb a low-boiling gas component, is 15 to 25% of the pores having a diameter of 100 Å or less (see JP-2007-2709 A).
In the activated carbon according to the related art, the volume of the pores of 20 Å or less, in which butane tends to remain, is reduced to be as little as ever.
However, the present applicant focused on the fact that the pores of 20 Å or less, in which butane tends to remain, can effectively suppress leakage of a low-boiling fuel component such as butane to the atmosphere from the evaporated fuel treatment apparatus since the pores of 20 Å or less have low desorbability on the butane but also have high adsorbability on the butane. It is thus an object of the present invention to provide an evaporated fuel treatment apparatus which can further reduce blow-by of an evaporated fuel component to the outside from the evaporated fuel treatment apparatus.